EUGENE -- Oregon is at a loss for the reason behind its declining tackles for loss, a statistic that leading tackler Derrick Malone concedes he paid little attention to in 2013 yet has been his "biggest concern" this spring.

Oregon had 70 tackles for loss last season after 84 in 2012, 94 in 2011 and 96 in 2010. In 2008, the Ducks had 104.5 and in 2007, a whopping 122. (The outlier is 2009, with 82.) With the exception of a 14-game schedule in 2011, UO played 13 games each of those seasons.

The 2013 total is UO's lowest since 2006, when UO had 67 en route to a loss in the Las Vegas Bowl.

"That’s my biggest concern for myself personally is to make sure I run through my gaps sooner and be that playmaker I need to be," said Malone, a senior who had 2.5 tackles behind the line of scrimmage among his team-leading 105 overall last season. "I’m worried about getting more 'TFLs' and being more aggressive."

Seeing the decline is easier than finding its cause, it seems. Last week, new defensive coordinator Don Pellum cautioned that year-to-year comparisons can be apples-to-oranges because of personnel changes. But, he acknowledged, the decrease has caught his eye.

"I think it is significant because it’s our chance to get the offense out of rhythm, but I haven’t studied it the last couple years," Pellum said. "Every year the defense is different a little bit. If you’re not running those same stunts you’re not going to get those same results so I can’t put a finger on it."

In its two 2013 losses, Oregon averaged 3.0 tackles for loss, almost half as many (5.8) as it averaged in its 11 victories. In November, when criticism of the Ducks' defense peaked it was in part because Oregon's tackles for loss ebbed to their lowest point. Oregon had 15 tackles behind the line in its four games that month, compared to 22 in its first four games and 26 in October.

It isn't the end-all, be-all statistic the Ducks live and die by -- they needed zero to crush Tennessee, 59-14, for example -- but such tackles are an indicator of disruption, and one that is lower than UO's liking.

Here's one significant difference that Pellum and Malone each point to: Former linebacker Kiko Alonso is a hard man to replace in the middle.

Alonso is now a Buffalo Bills star who was named the Pro Football Writers Association's defensive rookie of the year after finishing third in the NFL with 159 tackles in 2013. According to Pellum, his coach at Oregon, and Malone, who was tasked with succeeding him, Alonso had something of a sixth sense for identifying a play and rushing between the gaps in the offensive line for a tackle. And that's not to forget about the 10 tackles for loss by fellow inside linebacker Michael Clay, who also departed after the 2012 season.

Alonso's 14.0 tackles for loss led Oregon in 2012, and many of them weren't designed blitzes. Instead, Pellum said, Oregon would allow Alonso to freelance because of his read-and-react prowess.

"(Kiko) was one of the best in the country at reading it," Pellum said. "Kiko could see things and we gave him more of a green light because that’s naturally what he did. If you ask about Derrick, Derrick’s not a Kiko player. Derrick’s going to give you a lot more blitzing from the outside and coverage so they’re different types of players."

In 2014 Oregon doesn't need to replace Alonso but it is trying to replace the 42 percent of tackles for loss it lost to graduation.

Why is why Malone is attempting to pattern his game more after Alonso than ever. The knee and right shoulder injuries Malone suffered last November have healed, he said, which has allowed him to seek a "green light" similar to Alonso's in addition to his more natural pass coverage skills.

"I wasn’t worried about TFLs too much last fall, I was making sure I was in the right gap and had everyone lined up and made the tackles I needed to make," Malone said. "But, you know, we have a higher standard, we need those TFLs.

"Mike Clay and Kiko had that really, really well and it’s going to carry over this year. We’re going to have way more TFLs and be way more aggressive."